The present invention relates generally to vibration sensors. More particularly, the present invention relates to a vibration sensor module having an integral magnet for attaching the vibration sensor to a machine.
Industrial and manufacturing facilities typically employ large electrically powered machines to provide the horsepower and motive forces needed for production. Proper operation of such machines is often essential to meeting production needs. To this end, production facilities often adopt predictive maintenance programs in which machines are periodically monitored to ensure proper operation. Many predictive maintenance programs employ vibration analysis as a way to assess the health of the machine. During vibration analysis, a vibration sensor, or accelerometer, is positioned against the machine to be monitored and the accelerometer output is analyzed to detect the presence of anomalous operating conditions.
A variety of methods are used for maintaining contact between the accelerometer and the machine being monitored. For example, the accelerometer can be configured to be manually held against the machine as data is taken. Other methods allow for permanent attachment of the accelerometer to the machine (such as by threaded fastener or adhesive) to enable hands-free taking of data. However, such permanent mounting methods are less than desirable due to the labor and costs involved, and the use of attachment methods which do not permanently affix the accelerometer to the machine have historically proven to be disadvantageous as a result of poor sensor response.
Therefore, there is a need for an effective method of non-permanently attaching a vibration sensor to a machine.
The present invention eliminates the difficulties and disadvantages of the prior art by configuring a vibration sensor to be non-permanently attached to a machine. In accordance with a preferred embodiment of the invention, the inventive vibration sensor apparatus includes a housing having a first end and a second end. A magnet for magnetically and removably attaching the apparatus to a machine is disposed within the housing adjacent the first end and rigidly affixed thereto. A vibration sensor disposed within the housing adjacent the magnet senses vibration produced by the machine and outputs a sensor signal corresponding to the sensed vibration. The vibration sensor, which may be a single axis or a multiple axis sensor, is in rigid relation to the magnet and electrically isolated therefrom. Also disposed within the housing is a conditioning circuit for conditioning the sensor signal. At the resonant frequency of the apparatus, the conditioned sensor signal preferably has a gain of less than 20 dB relative to the sensor""s linear response range. A connector adjacent the second end of the housing enables a peripheral device, such as a portable data collector, to access the sensor signal over a broad frequency band.
In accordance with one aspect of the preferred embodiment, the sensor signal may be output by the vibration sensor in the form an electrical charge. In the conditioning circuit, a filter (such as a two-pole, low pass filter) attenuates the sensor signal thereby providing acceptable response at the resonant frequency. The filtered sensor signal produced by the conditioning circuit is in the form of an electrical charge. A converter receives the filtered sensor signal and converts it from an electrical charge to a corresponding voltage for use by the peripheral device.
To enhance the stability of the apparatus when being attached to an uneven machine surface, a plurality of feet are rigidly attached to the first end of the housing so that both feet contact the machine surface when the apparatus is magnetically attached to the machine.